1gitremote-helpers(1) 2==================== 3 4NAME 5---- 6gitremote-helpers - Helper programs to interact with remote repositories 7 8SYNOPSIS 9-------- 10[verse] 11'git remote-<transport>' <repository> [<URL>] 12 13DESCRIPTION 14----------- 15 16Remote helper programs are normally not used directly by end users, 17but they are invoked by Git when it needs to interact with remote 18repositories Git does not support natively. A given helper will 19implement a subset of the capabilities documented here. When Git 20needs to interact with a repository using a remote helper, it spawns 21the helper as an independent process, sends commands to the helper's 22standard input, and expects results from the helper's standard 23output. Because a remote helper runs as an independent process from 24Git, there is no need to re-link Git to add a new helper, nor any 25need to link the helper with the implementation of Git. 26 27Every helper must support the "capabilities" command, which Git 28uses to determine what other commands the helper will accept. Those 29other commands can be used to discover and update remote refs, 30transport objects between the object database and the remote repository, 31and update the local object store. 32 33Git comes with a "curl" family of remote helpers, that handle various 34transport protocols, such as 'git-remote-http', 'git-remote-https', 35'git-remote-ftp' and 'git-remote-ftps'. They implement the capabilities 36'fetch', 'option', and 'push'. 37 38INVOCATION 39---------- 40 41Remote helper programs are invoked with one or (optionally) two 42arguments. The first argument specifies a remote repository as in Git; 43it is either the name of a configured remote or a URL. The second 44argument specifies a URL; it is usually of the form 45'<transport>://<address>', but any arbitrary string is possible. 46The 'GIT_DIR' environment variable is set up for the remote helper 47and can be used to determine where to store additional data or from 48which directory to invoke auxiliary Git commands. 49 50When Git encounters a URL of the form '<transport>://<address>', where 51'<transport>' is a protocol that it cannot handle natively, it 52automatically invokes 'git remote-<transport>' with the full URL as 53the second argument. If such a URL is encountered directly on the 54command line, the first argument is the same as the second, and if it 55is encountered in a configured remote, the first argument is the name 56of that remote. 57 58A URL of the form '<transport>::<address>' explicitly instructs Git to 59invoke 'git remote-<transport>' with '<address>' as the second 60argument. If such a URL is encountered directly on the command line, 61the first argument is '<address>', and if it is encountered in a 62configured remote, the first argument is the name of that remote. 63 64Additionally, when a configured remote has 'remote.<name>.vcs' set to 65'<transport>', Git explicitly invokes 'git remote-<transport>' with 66'<name>' as the first argument. If set, the second argument is 67'remote.<name>.url'; otherwise, the second argument is omitted. 68 69INPUT FORMAT 70------------ 71 72Git sends the remote helper a list of commands on standard input, one 73per line. The first command is always the 'capabilities' command, in 74response to which the remote helper must print a list of the 75capabilities it supports (see below) followed by a blank line. The 76response to the capabilities command determines what commands Git uses 77in the remainder of the command stream. 78 79The command stream is terminated by a blank line. In some cases 80(indicated in the documentation of the relevant commands), this blank 81line is followed by a payload in some other protocol (e.g., the pack 82protocol), while in others it indicates the end of input. 83 84Capabilities 85~~~~~~~~~~~~ 86 87Each remote helper is expected to support only a subset of commands. 88The operations a helper supports are declared to Git in the response 89to the `capabilities` command (see COMMANDS, below). 90 91In the following, we list all defined capabilities and for 92each we list which commands a helper with that capability 93must provide. 94 95Capabilities for Pushing 96^^^^^^^^^^^^^^^^^^^^^^^^ 97'connect':: 98 Can attempt to connect to 'git receive-pack' (for pushing), 99 'git upload-pack', etc for communication using 100 git's native packfile protocol. This 101 requires a bidirectional, full-duplex connection. 102+ 103Supported commands: 'connect'. 104 105'push':: 106 Can discover remote refs and push local commits and the 107 history leading up to them to new or existing remote refs. 108+ 109Supported commands: 'list for-push', 'push'. 110 111'export':: 112 Can discover remote refs and push specified objects from a 113 fast-import stream to remote refs. 114+ 115Supported commands: 'list for-push', 'export'. 116 117If a helper advertises 'connect', Git will use it if possible and 118fall back to another capability if the helper requests so when 119connecting (see the 'connect' command under COMMANDS). 120When choosing between 'push' and 'export', Git prefers 'push'. 121Other frontends may have some other order of preference. 122 123'no-private-update':: 124 When using the 'refspec' capability, git normally updates the 125 private ref on successful push. This update is disabled when 126 the remote-helper declares the capability 'no-private-update'. 127 128 129Capabilities for Fetching 130^^^^^^^^^^^^^^^^^^^^^^^^^ 131'connect':: 132 Can try to connect to 'git upload-pack' (for fetching), 133 'git receive-pack', etc for communication using the 134 Git's native packfile protocol. This 135 requires a bidirectional, full-duplex connection. 136+ 137Supported commands: 'connect'. 138 139'fetch':: 140 Can discover remote refs and transfer objects reachable from 141 them to the local object store. 142+ 143Supported commands: 'list', 'fetch'. 144 145'import':: 146 Can discover remote refs and output objects reachable from 147 them as a stream in fast-import format. 148+ 149Supported commands: 'list', 'import'. 150 151'check-connectivity':: 152 Can guarantee that when a clone is requested, the received 153 pack is self contained and is connected. 154 155If a helper advertises 'connect', Git will use it if possible and 156fall back to another capability if the helper requests so when 157connecting (see the 'connect' command under COMMANDS). 158When choosing between 'fetch' and 'import', Git prefers 'fetch'. 159Other frontends may have some other order of preference. 160 161Miscellaneous capabilities 162^^^^^^^^^^^^^^^^^^^^^^^^^^ 163 164'option':: 165 For specifying settings like `verbosity` (how much output to 166 write to stderr) and `depth` (how much history is wanted in the 167 case of a shallow clone) that affect how other commands are 168 carried out. 169 170'refspec' <refspec>:: 171 For remote helpers that implement 'import' or 'export', this capability 172 allows the refs to be constrained to a private namespace, instead of 173 writing to refs/heads or refs/remotes directly. 174 It is recommended that all importers providing the 'import' 175 capability use this. It's mandatory for 'export'. 176+ 177A helper advertising the capability 178`refspec refs/heads/*:refs/svn/origin/branches/*` 179is saying that, when it is asked to `import refs/heads/topic`, the 180stream it outputs will update the `refs/svn/origin/branches/topic` 181ref. 182+ 183This capability can be advertised multiple times. The first 184applicable refspec takes precedence. The left-hand of refspecs 185advertised with this capability must cover all refs reported by 186the list command. If no 'refspec' capability is advertised, 187there is an implied `refspec *:*`. 188 189'bidi-import':: 190 This modifies the 'import' capability. 191 The fast-import commands 'cat-blob' and 'ls' can be used by remote-helpers 192 to retrieve information about blobs and trees that already exist in 193 fast-import's memory. This requires a channel from fast-import to the 194 remote-helper. 195 If it is advertised in addition to "import", Git establishes a pipe from 196 fast-import to the remote-helper's stdin. 197 It follows that Git and fast-import are both connected to the 198 remote-helper's stdin. Because Git can send multiple commands to 199 the remote-helper it is required that helpers that use 'bidi-import' 200 buffer all 'import' commands of a batch before sending data to fast-import. 201 This is to prevent mixing commands and fast-import responses on the 202 helper's stdin. 203 204'export-marks' <file>:: 205 This modifies the 'export' capability, instructing Git to dump the 206 internal marks table to <file> when complete. For details, 207 read up on '--export-marks=<file>' in linkgit:git-fast-export[1]. 208 209'import-marks' <file>:: 210 This modifies the 'export' capability, instructing Git to load the 211 marks specified in <file> before processing any input. For details, 212 read up on '--import-marks=<file>' in linkgit:git-fast-export[1]. 213 214'signed-tags':: 215 This modifies the 'export' capability, instructing Git to pass 216 '--signed-tags=verbatim' to linkgit:git-fast-export[1]. In the 217 absence of this capability, Git will use '--signed-tags=warn-strip'. 218 219 220 221COMMANDS 222-------- 223 224Commands are given by the caller on the helper's standard input, one per line. 225 226'capabilities':: 227 Lists the capabilities of the helper, one per line, ending 228 with a blank line. Each capability may be preceded with '*', 229 which marks them mandatory for Git versions using the remote 230 helper to understand. Any unknown mandatory capability is a 231 fatal error. 232+ 233Support for this command is mandatory. 234 235'list':: 236 Lists the refs, one per line, in the format "<value> <name> 237 [<attr> ...]". The value may be a hex sha1 hash, "@<dest>" for 238 a symref, or "?" to indicate that the helper could not get the 239 value of the ref. A space-separated list of attributes follows 240 the name; unrecognized attributes are ignored. The list ends 241 with a blank line. 242+ 243See REF LIST ATTRIBUTES for a list of currently defined attributes. 244+ 245Supported if the helper has the "fetch" or "import" capability. 246 247'list for-push':: 248 Similar to 'list', except that it is used if and only if 249 the caller wants to the resulting ref list to prepare 250 push commands. 251 A helper supporting both push and fetch can use this 252 to distinguish for which operation the output of 'list' 253 is going to be used, possibly reducing the amount 254 of work that needs to be performed. 255+ 256Supported if the helper has the "push" or "export" capability. 257 258'option' <name> <value>:: 259 Sets the transport helper option <name> to <value>. Outputs a 260 single line containing one of 'ok' (option successfully set), 261 'unsupported' (option not recognized) or 'error <msg>' 262 (option <name> is supported but <value> is not valid 263 for it). Options should be set before other commands, 264 and may influence the behavior of those commands. 265+ 266See OPTIONS for a list of currently defined options. 267+ 268Supported if the helper has the "option" capability. 269 270'fetch' <sha1> <name>:: 271 Fetches the given object, writing the necessary objects 272 to the database. Fetch commands are sent in a batch, one 273 per line, terminated with a blank line. 274 Outputs a single blank line when all fetch commands in the 275 same batch are complete. Only objects which were reported 276 in the output of 'list' with a sha1 may be fetched this way. 277+ 278Optionally may output a 'lock <file>' line indicating a file under 279GIT_DIR/objects/pack which is keeping a pack until refs can be 280suitably updated. 281+ 282If option 'check-connectivity' is requested, the helper must output 283'connectivity-ok' if the clone is self-contained and connected. 284+ 285Supported if the helper has the "fetch" capability. 286 287'push' +<src>:<dst>:: 288 Pushes the given local <src> commit or branch to the 289 remote branch described by <dst>. A batch sequence of 290 one or more 'push' commands is terminated with a blank line 291 (if there is only one reference to push, a single 'push' command 292 is followed by a blank line). For example, the following would 293 be two batches of 'push', the first asking the remote-helper 294 to push the local ref 'master' to the remote ref 'master' and 295 the local 'HEAD' to the remote 'branch', and the second 296 asking to push ref 'foo' to ref 'bar' (forced update requested 297 by the '+'). 298+ 299------------ 300push refs/heads/master:refs/heads/master 301push HEAD:refs/heads/branch 302\n 303push +refs/heads/foo:refs/heads/bar 304\n 305------------ 306+ 307Zero or more protocol options may be entered after the last 'push' 308command, before the batch's terminating blank line. 309+ 310When the push is complete, outputs one or more 'ok <dst>' or 311'error <dst> <why>?' lines to indicate success or failure of 312each pushed ref. The status report output is terminated by 313a blank line. The option field <why> may be quoted in a C 314style string if it contains an LF. 315+ 316Supported if the helper has the "push" capability. 317 318'import' <name>:: 319 Produces a fast-import stream which imports the current value 320 of the named ref. It may additionally import other refs as 321 needed to construct the history efficiently. The script writes 322 to a helper-specific private namespace. The value of the named 323 ref should be written to a location in this namespace derived 324 by applying the refspecs from the "refspec" capability to the 325 name of the ref. 326+ 327Especially useful for interoperability with a foreign versioning 328system. 329+ 330Just like 'push', a batch sequence of one or more 'import' is 331terminated with a blank line. For each batch of 'import', the remote 332helper should produce a fast-import stream terminated by a 'done' 333command. 334+ 335Note that if the 'bidi-import' capability is used the complete batch 336sequence has to be buffered before starting to send data to fast-import 337to prevent mixing of commands and fast-import responses on the helper's 338stdin. 339+ 340Supported if the helper has the "import" capability. 341 342'export':: 343 Instructs the remote helper that any subsequent input is 344 part of a fast-import stream (generated by 'git fast-export') 345 containing objects which should be pushed to the remote. 346+ 347Especially useful for interoperability with a foreign versioning 348system. 349+ 350The 'export-marks' and 'import-marks' capabilities, if specified, 351affect this command in so far as they are passed on to 'git 352fast-export', which then will load/store a table of marks for 353local objects. This can be used to implement for incremental 354operations. 355+ 356Supported if the helper has the "export" capability. 357 358'connect' <service>:: 359 Connects to given service. Standard input and standard output 360 of helper are connected to specified service (git prefix is 361 included in service name so e.g. fetching uses 'git-upload-pack' 362 as service) on remote side. Valid replies to this command are 363 empty line (connection established), 'fallback' (no smart 364 transport support, fall back to dumb transports) and just 365 exiting with error message printed (can't connect, don't 366 bother trying to fall back). After line feed terminating the 367 positive (empty) response, the output of service starts. After 368 the connection ends, the remote helper exits. 369+ 370Supported if the helper has the "connect" capability. 371 372If a fatal error occurs, the program writes the error message to 373stderr and exits. The caller should expect that a suitable error 374message has been printed if the child closes the connection without 375completing a valid response for the current command. 376 377Additional commands may be supported, as may be determined from 378capabilities reported by the helper. 379 380REF LIST ATTRIBUTES 381------------------- 382 383The 'list' command produces a list of refs in which each ref 384may be followed by a list of attributes. The following ref list 385attributes are defined. 386 387'unchanged':: 388 This ref is unchanged since the last import or fetch, although 389 the helper cannot necessarily determine what value that produced. 390 391OPTIONS 392------- 393 394The following options are defined and (under suitable circumstances) 395set by Git if the remote helper has the 'option' capability. 396 397'option verbosity' <n>:: 398 Changes the verbosity of messages displayed by the helper. 399 A value of 0 for <n> means that processes operate 400 quietly, and the helper produces only error output. 401 1 is the default level of verbosity, and higher values 402 of <n> correspond to the number of -v flags passed on the 403 command line. 404 405'option progress' \{'true'|'false'\}:: 406 Enables (or disables) progress messages displayed by the 407 transport helper during a command. 408 409'option depth' <depth>:: 410 Deepens the history of a shallow repository. 411 412'option followtags' \{'true'|'false'\}:: 413 If enabled the helper should automatically fetch annotated 414 tag objects if the object the tag points at was transferred 415 during the fetch command. If the tag is not fetched by 416 the helper a second fetch command will usually be sent to 417 ask for the tag specifically. Some helpers may be able to 418 use this option to avoid a second network connection. 419 420'option dry-run' \{'true'|'false'\}: 421 If true, pretend the operation completed successfully, 422 but don't actually change any repository data. For most 423 helpers this only applies to the 'push', if supported. 424 425'option servpath <c-style-quoted-path>':: 426 Sets service path (--upload-pack, --receive-pack etc.) for 427 next connect. Remote helper may support this option, but 428 must not rely on this option being set before 429 connect request occurs. 430 431'option check-connectivity' \{'true'|'false'\}:: 432 Request the helper to check connectivity of a clone. 433 434SEE ALSO 435-------- 436linkgit:git-remote[1] 437 438linkgit:git-remote-testgit[1] 439 440GIT 441--- 442Part of the linkgit:git[1] suite